Assay-furnace.



No- 798,949. PATENTED SEPT. 5, 1906. W. W. CASE.

ASSAY FURNACE.

APPLICATION FILED MAE.11,1905.

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PATENTED SEPT. 5, 1905.

W. W. CASE. ASSAY FURNACE.

APPLICATION mum 11,111.11. 1905,

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PATENTED SEPT. 5, 1905.

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ASSAY-FURNACE.

Specification of Letters Patent.

Patented Sept. 5, 1905.

Application filed March 11, 1905. Serial No. 249,628.

To all lH/LOHI/ it may concern:

Be it known that LWVILLIs WV. Case, a citi- Zen of the United States, residing at Denver, in the county of Den verand State of Colorado, have invented certain new and useful Improvements in Assay-Furnaces; and I do hereby declare the following to bea full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to improvements in assay-furnaces; and the object of my invention is to provide asimple and economical furnace which may be used either as a crucible-furnace or as a muffle-furnace or as both combined, the design of the invention being that all the crucibles shall be heated up evenly and that all parts of the muffleshall also be heated up evenly at the same time, the difficulty in the two being that the crucibles next to the burner generally heat up faster than the other crucibles and that the rear end of the muiile is usually heated to a higher degree than the front or mouth of the muffle by reason of its having to be kept open part of the time to supply air for oxidizing purposes. By my invention these diificulties are completely removed, as will be hereinafter fully set forth.

\Vith the objects stated in view my invention consists in the construction and combinations of parts, as hereinafter described and claimed.

In theaccompanying drawings, Figure 1 is a top plan view of my improved furnacev Fig. 2 is a cross-section of the same on the line 2 2 of Fig. 1. Fig. 3is a horizontal section of the same on the line 3 3 of Fig. 2. Figs. l, 5, and 6 show modified forms of the parts used as com bined supports and auxiliary heaters. Fig. 7 is a longitudinal section of my furnace as applied to a mufile alone, omitting the crucibles. Fig. 8 is a horizontal section of the same, taken on the line 8 S of Fig. 9. Fig. 9 is a crosssection of the same, and Fig. 10 is a horizontal section of a modified form.

a represents the wall of the furnace, which is composed, as usual, of refractory material. This furnace is hollowed out inside for the reception of the crucibles and the muffle. The shape and working of the crucible part of my furnace is substantially the same as that set forth in an application of even date herewith, Serial No. 24:9,629. The interior part of the furnace, which is hollowed out for the reception of the crucibles, is practically in the shape of a rectangle for the reception of two rows of crucibles which overlap each other. By the particular arrangement herein shown a greater number of crucibles can be used than has heretofore been the practice, as fully set forth in my said application of even date. The part of the furnace which receives the crucibles I) is open at the top and is adapted to be closed by removable covers 0, as described in my said application. The sides ofthe wall are built in so as to fit around a part of the crucibles, as fully described in my said application. The muffle, which is practically of the usual shape, is contained in a second open space (Z, which communicates with the open space 11, in which the crucibles are placed, the sole separation between said spaces being one of the side walls of the muiile itself, and at the top and the rear of this side where the mufiie meets the wall of the furnace, as shown at f, a luting of fire-clay is provided to prevent the gases from escaping through this point of union. The flame is admitted into the space 6 through the opening g, 71. representing a burner for gas or liquid hydrocarbon of any usual or approved type. This opening 9 is near the bottom of the furnace and at one end thereof, as shown in Figs. 1 and 2, and the main portion of the flame is by its own force blown through to the forward part of the channel that is below and between the crucibles, although a portion of course plays up into the space between the crucibles. The left-hand row of crucibles and the end crucible of the right-hand row are supported upon a bench i, cut away, as shown at f, for the freer passage of the gases. Of the right-hand row of crucibles those nearest the burner are supported upon a solid bench L and those opposite the muffle, except the last one, are supported on a bridge on, of which 1, Fig. 3, represents the abutment, the bridge being cut away to permit the passage of the flame and products of combustion on either side of the abutment l. The mufiic itself is supported upon separate pieces which are provided with projections or heaters, on which heaters the muiiie rests and which heaters are highly heated by the passage around them of the gases. These projections are placed just as close together as is consistent with the proper circulation of the gases, the idea being that these projections will become highly heated, even to the point of incandescence, and will thereby act in the manner of a clean coke fire directly under the muflie itself to heat it. These projections may be of any desired shape and of a volume of about one cubic inch each, or less for smaller work. These projections act as heaters, and by means of the construction described I have succeeded in quickly and evenly heating up to a highly-satisfactory degree a muffle fourteen inches wide, eighteen inches long, and seven inches high--a feat which has never been accomplished before by the use of gas or hydrocarbon fuel, the largest size of muffle hitherto used being ten inches wide by sixteen inches long and seven inches high, and that only slowly and with the greatest difficulty. In Fig. 6 is represented one form of these projections or supports. In Fig. 5 is represented another form, and in Fig. 4 is represented a number of these projections 02-, separated from each other by channels 9 and by other channels 5;. A number of such pieces arranged side by side, each provided with projections or heaters n, are shown in Fig. 2.

On the interior of the side wall of the furnace opposite to the crucibles and adjacent to one side of the muflle I form a number of ribs 1', having spaces 8 between them. These ribs and spaces gradually diminish in size from the mouth of the muffle toward the rear thereof in order to afford a freer passage for the gases near the mouth of the muflie, where the cooling effect of the air entering the muffle is the greatest, so that the greatest portion of the heat is concentrated near the mouth of the muflie.

The sole exit for the gases of combustion is the narrow annular opening 6 in thetop of the furnace, which is at the top of a passage which is preferably enlarged toward the interior of the furnace and funnel-shaped, as shown in Fig. 2, and within this opening is contained a cylindrical pipe at, which fits into a hole in the top of the muflle near its rear end. By reason of the factthat the gases of combustion escape through a narrow annular opening around the discharge pipe of the muflie a vacuum is created whereby the air on the ejector principle is drawn through the muflle, thereby creating and maintaining an oxidizing atmosphere within the muffle itself for cupeling and scorifying. By reason of the large number of heaters and the arrangement of the ribs and passages in the wall of the furnace, as already described, the heat in the muffle is maintained at the desired degree and kept uniform from the mouth to the rear notwithstanding the large amount of air passing through the muffle due to the ejector action of the burned gases.

One great difliculty hitherto encountered in the use of muffle furnaces is that it has been hard to maintain the proper oxidizing atmosphere and requisite heat for cupeling and scorifying, and before my invention it has been found necessary to use on all mufflefurnaces a discharge-pipe for creating a draft through the muflie, either extending into the open air or connected with the chimney. By

' my invention no such discharge-pipe is need ed.

The action of the furnace is as follows: Flame from gas or liquid hydrocarbon is forcibly blown in through the burner it. By its own force the major portion of the flame passes along underneath the crucibles, heating them as it passes, until it reaches the space opposite the muffle, where it divides, the major portion, however, going on beyond the abutment Z, both on account of the force of the blast and because the spaces 8 nearest the mouth of the muffle are the largest. This brings the greatest heat, so far as the muffle is concerned, at the mouth thereof, which is greatly to be desired. The flame as it passes underneath the muffle not only heats up the muffle in the usual way, but the greater part of its heat which is not absorbed as it rushes past the refractory non-heat-conducting muffle is intercepted by the projections or heaters 11., which are heated to incandescence, and by radiation and conduction of great additional heat the entire muflie is heated to a very high uniform degree, the result being that both the crucibles and the mufHeare at the same time uniformly brought up to a working heat.

In the drawings I have represented eight crucibles. I wish it to be understood, however,

that I can use a much greater number than this,if desired,and in small furnaces a less number may be used. In one form of small furnace only four crucibles are used, and in that case the crucibles would be arranged directly opposite the muffle and the gases would be introduced in the direction indicated by the arrow Q) in Fig. 1.

In Figs. 7, 8, and 9 is shown a modified form of furnace in which the crucibles are omitted. In this case the flame is brought in through a central channel 1, located considerably below the muffie itself. The flame enters at the rear of the furnace and is blown through the channel 1 toward the mouth of the muffle, which is supported on projections or heaters 2 and 4, (resting on a base 3,) separated by channels running at right angles to each other, as already described. lmmediately under the mouth of the muffle are arranged two crosspieces or heaters of the type shown by Fig. 6, one on each side of the channel 1, each piece consisting of a base and two upwardly-projecting walls 4:, leaving a channel 5 between them and at each side for the purpose of directing the gases of combustion outward around the mouth of the muffle, and these pieces act as larger heaters for the mouth of the muffle. Along the side walls of the furnace are arranged ribs 6, separated by spaces 7 which spaces and ribs are largest near the mouth of the muffle and gradually diminish in size toward the rear. At the rearmost portion these may be omitted, if desired, as shown in Fig. 8, the construction being similar to that already described in connection with Figs. 1, 2, and 3.

The gases of combustion escape through a narrow annular slit 8, which surrounds an open cylindrical pipe 9, which is connected to the top and rear of the muffle. I do not restrict myself, however, to a cylindrical pipe, as a square pipe would answer the purpose.

In Fig. IOis shown a modified form in which the flame instead of being admitted at the rear of the furnace is admitted at the side, as shown at 10. This form I use where the muffle very wide in proportion to its length.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent of the United States, is-

1. In an assay-furnace, the combination with the walls thereof, of a muffle supported therein, means for supplying the major portion of the heat derived from the fuel around the mouth of the muffle and supplying itin lesser amounts toward the rear of the muffle, said means including heaters placed as closely together as is consistent with the circulation of the products of combustion, said heaters being adjacent to the muffle and heating the same in the manner of a clean coke fire, substantially as described.

2. In an assay-furnace, the combination with the walls thereof, and a muffle supported within said walls, and means for heating all parts of said muffle uniformly, comprising a large number of heaters placed as closely together as is consistent with the circulation of the products of combustion and located adjacent to said muffle, said walls being provided with ribs and passages diminishing in size from the mouth of said muffle toward the rear thereof, substantially as described.

3. ln an assay furnace, the combination with the walls thereof hollowed out internally, of a series of crucibles and a muflle mounted in said furnace, one of the side walls of said muffle serving to divide the working space of said muffle from the crucible-containingspace of the furnace, supports for said crucibles. and a large number of heaters arl l l ing near the bottom for the reception of a flame, and with an opening in the top for the insertion of crucibles, of a cover for said furnace, crucibles located in said furnace, supports for said crucibles, a muffle located in said furnace, one of the side walls of the muffle serving as a partition toseparate the working space of the muffle from the crucible-containing space of the furnace, and means for heating up said muffle evenly from the mouth to the rear, consisting of a large number of heaters arranged adjacent to said muffle, said wall being provided with ribs and passages diminishing in size from the mouth of the muffle toward the rear thereof, substantially as described.

5. In an assay-furnace, the combination of the walls thereof and a top, said top being provided with a single escape-opening, a muffie mounted in said furnace and provided with adischarge-pipe near its rear end, the passage surrounding said pipe for the escape of the products of combustion being annular in shape and surrounding the discharge-pipe of the muffle, whereby the escape of the gases of combustion form a vacuum and act as an ejector draw the air through the muffle, thus producing an oxidizing atmosphere in the same, substantially as described.

6. In an assay-furnace, the combination with the Walls thereof provided with ribs and passages of varying size, a muffle supported in said furnace, said furnace being provided with a single exit for the gases of combustion, and said muffle being provided with a discharge-pipe located centrally in said exitopening, whereby the outrush of the gases of combustion causes a current of air through said muffle, and means for maintaining a uniform heat from the mouth to the rear of said muffle, consisting of a large number of heaters arranged adjacent to said muffle and acting in connection with the ribs and passages already mentioned, substantially as described.

In testimony whereof I affix my signature in ranged closely together located adjacent to presence of two witnesses. said muffle, substantially as described.

I. In an assay-furnace, the combination of the walls thereof hollowed out internally, provided with an opening in the top for the escape of the gases of combustion, with an open- ILLIS \V. CASE.

\Vitnesses:

A. L. l'louuu, LANEU (f. OGDEN. 

